The paper focuses on the cyclic strength of the dense sand formations encountered at the Oseberg and Gullfaks fields, located in the relatively shallow waters of the Shetland shelf, west of the deeper Norwegian Trench. Due to the dense and stiff nature of these formations, shallow foundations have been the preferred solution for offshore structures within this area. A dataset of 36 cyclic anisotropically consolidated triaxial tests performed on reconstituted sand specimens is herein used to calibrate a simple model expressing the cyclic strength of these dense sandy formations as a function of few key variables, such as cyclic and average stress amplitude, number of loading cycles and fines content. It should be however noted that the model focuses on cyclic failure due to build-up of cyclic strain, in soils subjected to a stress history typical of offshore gravity base foundations. Further, due to the limited number of tests on which the proposed model is based, direct use in design shall be considered with caution.
D. Bertalot, D. Soler Sandoval and G. Yetginer Tjelta
Keywords: cyclic loading, sands, North Sea
Publisher: DFI